(Bluewater) Flexible Flowline Risers – Operational Experience

1 FlexibleFlowlineRisers OperationalExperience Introduction&BackgroundtoUisgeGormInstal lation RiserReleaseIncident RecoveryBacktoProductionOperations Followup Summary QuestionsFPSOUISGEGORM Fife,Fergus,Flora,AngusFields 1995-2008 FieldLayoutGeneralArrangementTurretGener alArrangementTurretRiserReleaseIncidentJ uly07 P8riserwasat80 BarstaticpressurewiththeProductionWingVa lveclosed. , AllPOBmustered& ,&confirmedtheareawasallclearofgaswithno anomaliesnoted. Theemergencywasstooddownandfurtherinvest igationsrevealedoilywaterintheturretcana reawheretherisersterminatetopsides. Theareawasbarrieredoffandaccesstothecont aminatedarearestricted.

2 Duringfurthersiteinspectionbycrewtherewa snotedtobewaterintheTurretCan(attheriser terminationclamps) DSVmobilisedtosecurewellhead,&secureflow linetosafeguardinstallation&environment Commencedinvestigations Who-BW,Hess,MCS,Wellstream,NKT,Coflexip, Lloyds,theHSEpipelineauthorities&DBERR. What How physicalexamination-proposesolutions-tec hnicalreviews&riskassessments(TRA s)-OperationalRiskAssessments(ORA s)-Provideassuranceonshore(BW,Hess,Autho rities)&offshorethatsafesolutionsachieve d,andsafetorestart&continuetooperate. CommencedJuly31st2007,restartedproductio n(P13)&WIendSept2007,andremainingwellsby January2008 RecoveryProjectWhatHappened?

3 CrediblefailurescenariosconsideredbyBW/ Establishaprocessbywhichwecanassuresafer estartofproduction :FatigueFailureH2 SgaspermeationFreeCorrosionItubeAnnulusA nomaliesTopsidespipingfailuresRiserAnnul arGasReleaseFailureoftheinternalpressure BarrierFailureoftheoutersheathICPR eviewOperationalRiskAssessmentIssuescons idered(short&mediumterm) Failuremechanisms Operationalexcursions( ,Overtemperatureetc.,) Gaspermeabilityfrominnerboretoannularspa ceofriser Pipelinemaintenance Operationalmonitoring Chemicalmanagement MAPD andsafetycaseQRAreview WSEreview IntegritymanagementprocessreviewFlowline Assurances WellstreamWellstream(WI/P13/P15)(WI/P13/ P15)Riserannulusvacuumtestscarriedoutcon firmedthatWI& (pinholeleak) ,andoperatingstatusonP15, (Cont d) NKT(FergusandFlora)NKT(FergusandFlora) CoflexipCoflexip(AngusA14)(AngusA14)Fati gueanalysesconsideredtobeacceptableforco ntinuedservice,asbasedonafloodedriser& (opensubseacrossover).

4 ExamplesofMCSsupport MCST opsidePhotosTopsideimageofflexibleriserP 15P15 I-TubeInspectionNovisiblemajorexternalsh eathdamagesourcedneartopofI-tube(typical image)P15-EndFittingVentPortDetails WellstreamFlexibleRiser Noannulusventsysteminstalled 3x120 spacedannulusventportsmanufacturedonthef lexibleriserendfitting Twosetsofaccessportsaremanufacturedtoeac hofthe3ventports(verticalandhorizontal) HorizontalportslocatedjustaboveI-tubetop ,allofwhichremainpluggedsinceinstallatio n VacuumTestResultsandAnnulusStatusConclus ions VacuumTestcompletedtwicewithsimilarresul ts Circa60litresextractedbutonly20litresN2b ack-filled Resultsindicateafloodedannulusconditiont oLAT Nogrossexternalsheathdamageidentifiedatt heplashzone,possibilitytoreuseriserbased onfatiguecalculationsNogrossexternalshea thdamagefound[HOLD]FlexibleRiserP13P13 MCST opsidePhotosTopsideimageofflexibleriserP 13P13 MCSI-TubeInspectionNovisiblemajorexterna lsheathdamagesourcedneartopofI-tube(typi calimage)

5 P13-EndFittingVentPortDetails WellstreamFlexibleRiser Noannulusventsysteminstalled 3x120 spacedannulusventportsmanufacturedonthef lexibleriserendfitting Twosetsofaccessportsaremanufacturedtoeac hofthe3ventports(verticalandhorizontal) HorizontalportslocatedjustaboveI-tubetop ,allofwhichremainpluggedsinceinstallatio n VacuumTestResultsandAnnulusStatusConclus ions Vacuumtestresultssuccessful,whichindicat estheannulusstatusasnon-flooded NoexternalsheathdamageidentifiedFollowup Aspartoftheongoingoperationsplannedmaint enanceroutineswereintroducedtocarryoutpe riodicvacuumtesting,andItubeannularinspe ctions. Priortotheabovepmr sbeingcarriedout,theUisgeGormwasdecommis sionedin2008.

6 Aspartoftheriserremovalprocess,thetoppar toftheP8failedriserwasremoved& Risersinstalledwithadesignlifeof15years, gave11yearsservice. Inspectionregime,whichwasconsideredadequ ateinthe90 sbyindustrystandardsatthetimewasinrealit ynotadequateduetoanilinspectionwithinthe Ituberegion. UisgeGormreturnedtofullproductioninJanua ry2008followingarigorousassuranceprocess . UisgeGormdecommissionedmid2008,&